What is the speed of sound?
In dry air at 20°C, sound travels at about 343 meters per second, or about 1,235 km/h (767 mph). It moves faster in warmer air, in water and in solids.
Sound is a vibration that travels through a material by making particles bump into each other. The closer and more tightly linked the particles, the faster sound moves. In water, sound travels at about 1,480 meters per second, more than four times faster than in air, and in steel it can exceed 5,000 meters per second.
Temperature matters too. Sound travels slower in cold air, which is why the speed of sound is lower at the high altitudes where jets fly. Sound cannot travel through a vacuum at all, because there are no particles to carry it.
Breaking the sound barrier
An aircraft flying faster than sound creates shock waves heard on the ground as a sonic boom. US pilot Chuck Yeager first broke the sound barrier in level flight in 1947 in the Bell X-1. The speed of sound is called Mach 1.
Did You Know?
The crack of a whip is a tiny sonic boom. The tip of the whip moves faster than the speed of sound.